It is thought that the measurement is of Pictish origins, and is most common in the north east, and often absent in the south of Scotland.
The name "Haddo" is also a corruption of “Hauf Daugh”, or half-davoch, in turn a translation of “leth-dhabhach”.
An old farmer in Western Gaeldom frequently speaks of his fields, not as containing so many acres of land, but as ‘the sowing of so many bolls of oats’, ‘the bed of so many barrels of potatoes’ &c. Accordingly, from a measure of capacity, ‘dabhach’ came early to be used as a measure of land surface.
In Gaeldom, where arable land is scant and scattered, the variations in the acreage, of particular ‘dabhachs’ or ‘ounces’ must have been very great, still the extent of land represented by these terms seems to have been, as a rule, about 104 Scots acres, or 120 English acres [0.547 km2]”.The lexicographer Jamieson claimed that a daugh was enough to produce about 48 bolls, and averaged an area of approximately 1+1⁄2 square miles (3.9 km2).
Daughs are referred to in the Book of Deer, and were recorded as being in use in the late 18th century in Inverness-shire.